# filter any unwholesome file names 
my @reason;
push @reason, "... a file with that name doesn't exist"
    if ! -f $file;
push @reason, "... it starts with a dot"
    if $file =~ /^\./;
...

if (@reason) {
    warn "Rejecting filename '$file' because ";
    warn $_ for @reason;
    next;
};

##</code><code>##

$file =~ /^\w[-_\w]+\.\w+$/
    or push @reason, '... it doesn't look like a sane filename';